I demonstrate the numerous flaws in TAG here:

http://www.rationalresponders.com/ontological_and_epistemological_blunders_tag

However, a poster named "Prof" from the old Infidelguy site raises yet more problems with TAG. His original posts can be found here:

http://www.infidelguy.com/forumarchives/modules.php?name=Boards&file=viewtopic&t=21132&highlight=

Basically, Presuppers make these additional errors:

1) They fail to grasp that the assumption of uniformity of nature is considered to be only a necessary, not sufficient justification for induction, and thus the UON is not used as a justification for induction in the first place.

2) They misunderstand the actual problem of induction - it is not the circular relationship between induction and the 'uniformity of nature' but a concern about a logical connection between a sample and a population. No one uses the UON to justify induction.

3) Their attempts to 'solve' the 'problem of induction' by arguing for an assumption of uniformity of 'god' (the implication of presuppositionalism) therefore do not even address the actual 'problem', seeing as the UON isn't used to justify induction in the first place! Furthermore, the UOG argument leads to even greater problems than using the UON to justify induction.

4) Finally, they fail to grasp that it is a mistake to presume that a failure to provide an adequate justification for induction leaves us without any grounds to rely on induction other than 'faith': The fact one cannot provide a justification for a system doesn't imply that one cannot know that the system is useful. A child is unable to prove that his name is his name; does this mean that he is without any grounds for holding that his name is his name? Knowledge and justification are two different philosophical concepts. The Problem of Induction relates to philosophical justification.

So many errors in one bad argument. Let's roll up our sleeve and begin.

From this page discussion Van Tillian presuppositionalism:

http://www.bible.org/page.asp?page_id=3644

We get the following quotes from Van Till:

“It is fatal to try to prove the existence of God by the ‘scientific method’ and by the ‘appeal to facts’ if . . . the scientific method itself is based upon a presupposition which excludes God."

and...

"Our argument as over against this would be that the existence of the God of Christian theism and the conception of his counsel as controlling all things in the universe is the only presupposition which can account for the uniformity of nature which the scientist needs. But the best and only possible proof for the existence of such a God is that his existence is required for the uniformity of nature and for the coherence of all things in the world."

This is not a rational grounds for justification, it is an appeal to magic. It does nothing to actually provide a justification, it merely asserts that there is one. One might as well say that there is a council of twelve, universe-creating elves (tm)" who create uniform universes. This universe being an example of their handiwork. That "accounts" for the universe being uniform just as cogently as does positing the Christian God: in other words, its just a label - a magic word - abracadbra- without any content behind it. "Goddidit"

Next, there is an utterly unsupported assertion contained with statements like these: "the God of Christian theism and the conception of his counsel as controlling all things in the universe is the only presupposition which can account for the uniformity of nature." It is the presumption that the uniformity of nature needs to be "accounted for." In other words, the implication is: "without a God, a universe wouldn't be uniform." But precisely on what basis is such an assumption made? Exactly what experience, or special insight, does the author have of universes forming, that give
him the grounds for sneaking in the implicit assumption that Universes without a God are not uniform? How many "non-uniform," "un-created" universes has he been privy to, on which to derive his assumption?

The answer would be "none." So where does this assumption come from? The error has two sources: the first, a confusion between being able to doubt a claim and unseating a claim. To bring a claim into doubt is not a grounds for unseating the claim on it's own. To confuse the ability to doubt for the ability to unseat is to commit the 'fallacy of arguing to uncertainty."

The next source for the error comes from the presupper's utter confusion as to what Hume's problem of induction actually is - which in turn stems from the fact that most people using this argument have never actually read Hume's Enquiry into the Human Understanding. So let's correct this second here: Whether or not there is a satisfactory philosophical justification for induction, there is nothing within this 'problem' that grants anyone an epistemic grounds to suppose that induction cannot work without a 'god' to sustain it.

So we have two amateurish errors here born of a basic ignorance of logic: an assumption that providing a 'label' answers a problem and the unwarranted assumption that a lack of a satisfactory justification for induction somehow grants the theist epistemic grounds for holding that induction cannot be justified without turning to a deux ex machina: a 'supernatural', nature-sustaining 'god'.

Now that we understand the level of ignorance behind presupper's misunderstanding of Hume is, let's continue:

The Presupper's Misunderstanding of the nature of the Problem of Induction

The presuppers protest they have a firm epistemology (theory of knowledge, which means they must have a theory of what knowledge is, how they "know" things, and the scope of knowledge). But when they fling the "problem of induction" in the face of the atheist, as if our worldview leaves it problematical while theirs offers a solution, the presupper reveals a naive understanding of the problem. They believe their solution; that God purportedly tells them nature will remain uniform - operate today as it did yesterday - justifies induction. In this they tend to mix up the problem of justifying a belief in the Uniformity of Nature (UN) with the problem of Induction itself (the latter being more of a logical/practical problem).

This much is true: Inductive inferences aren't much good if nature is not uniform, because if it's not, a principle you discovered via past experience couldn't give you insight to future experience (because there would be no uniform pattern to experience either future or past). So this leads to one other knock against induction - it needs the UN to work, but can not itself justify a belief in the UN. How can we know nature will remain operate tomorrow as it did today?

Well, if we say "because it has been uniform in my experience so far" you are using induction to establish the uniformity of nature. The problem is of course that you are simultaneously presupposing nature is uniform in order to make the inductive argument that nature is uniform. So you are stuck in circular question-begging (in the classic understanding of this "problem").

But the presuppers assert they have an epistemological answer to the dilemma: The Christian presupp asserts that they needn't rely on question-begging induction to infer nature is uniform; their 'god' has given them the knowledge that nature is uniform through revelation and has promised it will remain so. Therefore, says the presupper, "in my world view I know nature will remain uniform via means other than induction, which means the UN is not established by question-begging assumptions. As well, the UN also justifies inductive reasoning. Thus my use of induction as a tool of gaining knowledge about the world is justified - something you can not say about your inductive inferences."

Two main problems start here. It starts with the fact that If the Christian adduces Hume's problem of induction as a real epistemological problem that needs a solution, then the Christian binds himself to solving the problem. However, the Christian has shot himself in the foot because he does not have a solution to the problem.

Here's why the Christian's proposal for establishing induction on God's promise of the UN is insufficient:

1. This is to actually ignore the fundamental "problem" of induction actually is (this is, if you are going with Hume, and some of those who followed, e.g. Popper, Russell etc). The Uniformity of Nature is necessary for induction but it is not a sufficient justification of inductive inference, therefore, the circularity problem is actually a moot issue, seeing as the assumption of a uniformity of nature could never solve the problem in the first place. That is precisely why modern philosophers do not rely on it as a 'solution' in the first place.

The actual knock against induction is that there is no valid logical "connection" between a collection of past experiences and what will be the case in the future. The classic "white swans" example serves: the fact that every swan you've seen in the past was white means simply that: every swan you've seen has been white. There is no logical "therefore" to bridge the connection "all the swans I've seen are white" to "all swans are white" (or "the next swan I encounter will be white").

As Hume pointed out, it may be our habit to make such leaps, and it may have so far been fairly useful to do so up to now, but there is no actual logical justification for doing so. We just do it (use make inductive inferences, from past experience to universal statements of knowledge) based on habit.

As Hume and others point out, this being the case, how can such an inductive inference from a bunch of past observations to universalizing "all swans are white" or predicting the future "the next swan I see will be white" count as knowledge? **

This epistemological quagmire is something that even the Uniformity of Nature simply doesn't solve. So if a presupper who has seen all white swans proclaims inductively: "All swans are white." ask:

"Really, does that count as knowledge? How do you know that?"

To which he'll answer...????....

If the presupper is going to say: "Well, all the swans in my past experience were white - I'm using induction, justified by my world view. I can use induction because my God promises nature will remain uniform, and therefore be intelligible to me."

Then say: "So?... Remember the problem of induction? There is no logical connection between having seen a bunch of white swans and your unwarranted logical leap to "all swans are white." Here you go, I will grant you "Nature will remain Uniform." Now...how does that justify your statement of knowledge that "all swans are white?"

Christian: "Well, all the swans I've seen so far are white so..."

"Yes...."?

Christian: "So, I'm making an inference to "all swans are white."

Which is logically unsupported. And that's what Hume was saying as anyone who's actually read him already knows.."

"THAT's the fundamental Problem of Induction (as opposed to the problem of logically establishing the uniformity of nature) . Yes induction presupposes the uniformity of nature, but while necessary, the UN is hardly sufficient to justify inductive inferences epistemologically. When the next swan turns out to be black, it shows your statement "all swans are white" had no more "knowledge" content then the same words coming out of my mouth. And you can justify calling it "knowledge" no better
than I can. What you've done is presupposed nature to be uniform, but not in fact justified any particular inductive inference you may wish to make (and that includes ANY inference, whether you are inferring all swans are white, or doing science and inferring from past experience gravitational computations that you are attempting to apply to future experience).

"So, in fact, the fundamental epistemological challenge has not been met by your Christian presupposition. Your purported "knowledge" that the world remains uniform provides no solution to the very problem of induction you lobbed at us atheists: the fundamental epistemological problem being "How do we know that we know something?"

And an even more fundamental problem for the Christian Presuppositionalist:

2. The Christian protests that atheists have no non-question-begging grounds upon which to argue the Uniformity of Nature (UN), and yet the Christian ignores he is in precisely the same situation. The Christian has been promise that nature will remain uniform by God, which means the Christian's belief in the Uniformity of Nature is hung upon...you guessed it...the Uniformity Of God (UOG).

If God is not uniform from one moment to the next, then He can hardly be relied on as the source of Uniformity in Nature. But how does one know that God will remain uniform tomorrow as today? Uh-oh, you aren't going to rely on what God said or did in the past to infer how He'll act in the future, are you? 'Cause, you know, that would be using induction - the very reasoning you are trying to justify. Same as if you appeal to any "inner experience" of God or whatever. Whenever you are appealing to something that happened "yesterday" (or now) to make a knowledge statement about tomorrow (or universalizing to that which you have not observed), you are making an inductive inference, and therefore begging the question you are supposed to be answering.

Simply take the "problem of induction" argument for the UN and insert the UOG instead, and you end up with precisely the same question-begging assumptions. Of any Christian who claims induction is justified by their God, ask how they justify the Uniformity Of God without question-begging...and watch them squirm. I've never, ever, once seen a Christian presuppositionalist do anything but ignore, flail, or just run away from this problem.

And if the Christian retreats to "Well, that's my point really, we all have our presuppositions...." then he's being disingenuous, because he'd made a challenge to atheist reasoning that the Christian himself can not meet. So why adduce the problem of induction, as if it were some sort of "gotcha" for atheists but not for Christians in the first place? (Let alone the unwarranted puffing of chests with which the Christian flings the POI at the atheist).

And the atheist can point out that for adressing the problem of induction, the presupposition of the Uniformity Of God (or that God isn't lying etc) in fact holds no more epistemological value - does no more epistemological "work" - than the simpler presupposition that Nature is Uniform. BOTH presuppositions appear to set the necessary (if not sufficient) rational for induction, but one (God) is infinitely less parsimonious (and parsimony is vital to creatures like us with limited knowledge/time spans, who thus have limited resources in being able to gather useful beliefs. A non-parsimonious approach to adding layers of explanation opens the Pandora's box to an infinity of logical possibilities, which we simply do not have the time or mental resources to handle). Not to mention that, in having to swallow the "pill" of the Bible whole in their presupposition, they behave inconsistently - on one hand saying their presupposition justifies reason, logic and evidential reasoning, then in the next breath ignoring any application of those tools when they show the bible to be in error.

So...Christian presuppositionalists not only do not solve the fundamental issues of induction; they typically don't even seem to understand what they are dealing with when they wield that particular "weapon" carelessly, as so many of them do.

Review of The Failure of the "Uniformity of god" Argument

It is particularly ironic that for presuppers to adduce Hume's Problem Of Induction, given that it lands them skewered on the same dilemma.

The Christian "solution" is "God told me (via the biblical revelation) that he promises to uphold the general uniformity and intelligibility of nature."

In doing this the Christian believes he has at once justified induction (because our inferences will be made against a universe that will act uniformly) AND avoided the essential problem of induction because their conclusion about the Uniformity Of Nature is not based upon induction; but upon revelation. They have a "third way" of knowledge, unacknowledged in our world view, which "solves" such epistemological problems.

But...even accepting this as true for the sake of argument.... they don't solve it! They've just slipped the problem back a step. The Christian has simply predicated the Uniformity Of Nature on the Uniformity Of (a) God (who will purportedly uphold the uniformity of nature). You ain't gonna have any uniformity of nature if the God upholding it isn't uniform Himself. So we can ask the same question to the Christian about the foundation for their belief in the uniformity of God: Leaving aside, for a moment, the insurmountable ontological problems with the 'god' term, on what non-question-begging grounds can you justify your expectation that God will keep his promise, or that God will be as he is tomorrow as he was yesterday?" You run into the same meta-problems that follow from using the uniformity of nature argument!*

On the same argument used by the presupper, the conclusion is inescapable: they can't do so. They ARE appealing to induction whether they refuse to acknowledge it or not.

In addition, simply appealing to "revelation" as some form of knowledge distinct from empirical, sense-based inference doesn't work, because the "problem of induction" is one of logic and reason - not one restricted to inferences based upon materialistic sense-input. In other words, it asks "what justifies an inference from past experience to future experience. And revelation is just one more form of experience. Whether the Christian encountered God's "revealed" claims in an old book, or whether he even wishes to claim God beamed an experience of revelation right into his mind...the same question is begged: "On what grounds do you have the expectation that your experience of God means that God will be the same tomorrow as it was today?"

If he simply retreats to "Well, part of my presupposition is that God is immutable" or some such nonsense, then he has still failed to justify or solve the problem of induction - he's just "presupposed" it away. He has offered no more rational justification than anyone else who holds the mere expectation that nature will remain uniform - the very expectation he says secularism fails to justify! And since the
Christian's God claim does absolutely no more epistemological duty than the mere presupposition that nature is uniform, he can hardly claim it's necessity. And we all tend to (as a matter of habit) presume nature will remain uniform anyway.

* As Howson & Urbach point out, assuming a uniformity of nature is a nonsolution, since it's a fairly empty assumption. For how is nature uniform? And what, really, are we talking about. What would really be needed are millions upon millions of uniformity assumptions for each item under discussion. We'd need one for the melting temperature of water, of iron, of nickel, etc, etc. For example "block of ice x will melt at 0 Celsius;" for these types of assumptions actually say something. Furthermore, the uniformity of nature assumptions fall prey to meta-uniformity issues - for how are we to know that nature will always be uniform? Well, we have to assume that too. And how do we know that the uniformity of nature is uniform? Ad infinitum. So, to "solve" induction by uniformity of nature solutions doesn't really work.